1. Field of the Invention
The present invention relates to an image pickup apparatus of a video camera or the like having a color separation matrix.
2. Related Background Art
Hitherto, there has been known a color filter such that complementary colors (magenta Mg, green G, cyan Cy, yellow Ye) as shown in FIG. 1 are arranged like a mosaic.
In an image pickup apparatus such as a video camera or the like having a CCD in which the color filter of the complementary color mosaic as mentioned above is arranged in front of the CCD, in order to finally obtain a luminance signal and color difference signals, by controlling the reading operation from the CCD in the following manner, predetermined image pickup (pixel) outputs which are obtained from the above complementary color filters are added, thereby reading out those signals.
That is, in even number fields, pixel outputs of the nth row and the (n+1)th row, which are neighboring in the vertical direction, are added each column and pixel outputs of the (n+2)th row and the (n+3)th row are added every column, thereby reading out the pixel outputs. In odd number fields, pixel outputs of the (n+1)th and (n+2)th rows and the (n+3)th and (n+4)th rows which are deviated by every row from the even number fields are respectively added every line, thereby reading out the pixel outputs.
Due to this, Mg+Cy=WB(R+G+2B) is derived from the portion of the nth row and the mth column of the even number field. G+Ye=GR(2G+R) is obtained from the portion of the nth row and the (m+1)th column. G+Cy=GB(2G+B) is obtained from the portion of the (n+1)th row and the mth column. Mg+Ye=WR(2R+G+B) is obtained from the portion of the (n+1)th row and the (m+1)th column.
On the other hand, G+Cy=GB(2G+B) is derived from the portion of the nth row and the mth column of the odd number field. Ye+Mg=WR(2R+G+B) is obtained from the portion of the nth row and the (m+1)th column. Cy+Mg=WB(R+G+2B) is derived from the portion of the (n+1)th row and the mth column. Ye+G=GR(2G+R) is obtained from the portion of the (n+1)th row and the (m+1)th column.
Further, in a processing circuit arranged at the post stage of the CCD, by adding or subtracting the four kinds of device outputs as mentioned above, the following luminance component signal and color difference component signals are obtained.
Luminance component signal: y=WB+GR/WR+GB PA1 Color difference component signals: EQU cr=WR-GB, cb=WB-GR
In the conventional video camera, the luminance component signal and the color difference component signals which were obtained as mentioned above are directly used as a luminance signal and color difference signals.
Different from the components which have been determined by the NTSC standard, the color difference component signals as mentioned above have a problem such that accurate color difference signals cannot be obtained and color reproducibility is bad.